Application Development for Freelancer

I need an experienced application developer to work on a project. The platform for this application is flexible and I'm open to suggestions. The main goal and purpose of the app will be discussed during the project with the developer.

The functionalities I want the application to have include:
- User Authentication
- Push Notifications
- In-app Purchases

I'm looking for an individual with a strong background in app development. Please provide examples of your previous work upon application.